Attachment system of aircraft components

ABSTRACT

An attachment system for attaching a component ( 11 ) such as a vertical tail plane to a fuselage ( 27 ) of an aircraft; the component ( 11 ) being structured as a box comprising front and rear spars ( 13, 14 ), ribs ( 15 ) extending from the front spar ( 13 ) to the rear spar ( 14 ), and a skin ( 17 ), and also comprising a plurality of intermediate spars ( 23 ) arranged to be attached to fuselage frames ( 33 ); the fuselage ( 27 ) comprising a skin ( 31 ) and frames ( 33 ) and also comprising a mounting arrangement suitable for receiving the additional spars ( 23 ) and for allowing its attachment to the frames ( 33 ).

FIELD OF THE INVENTION

The present invention relates to an attachment system of aircraft components and more in particular to an attachment system of a vertical tail plane to the aircraft fuselage.

BACKGROUND OF THE INVENTION

As is well known, weight is a fundamental aspect in the aeronautic industry, which industry, therefore, is increasingly using composite materials instead of metallic materials even for primary structures.

The composite materials that are mostly used in the aeronautical industry consist of fibers or fiber bundles embedded in a matrix of thermosetting or thermoplastic resin, in the form of a preimpregnated or “prepreg” material. The main advantages of using these composite materials are:

a) Their high specific strength with respect to metallic materials. It is the strength/weight equation.

b) Their excellent behavior under fatigue loads.

c) The possibilities of structural optimization due to the anisotropy of the material and the possibility of combining fibers with different orientations, allowing the design of the elements with different mechanical properties adjusted to the different needs in terms of applied loads.

The installation of the vertical tail plane onto the aircraft fuselage is made in a final assembly stage. Otherwise, logistic and transport requirements would increase time and costs. In the prior art, this installation of the vertical tail plane onto the aircraft fuselage has been typically made using specific fittings and/or superficial arrangements for coupling both components and transferring the loads from the vertical tail plane to the fuselage structure.

The known solutions for installing a vertical tail plane or other aircraft components or parts made with composite materials onto an aircraft fuselage also made with composite materials have followed the same approach that was used when these components were made with metallic materials: the use of specific superficial means made with metallic materials and/or composite materials for coupling both components and transferring the loads to the fuselage structure. This results in, among other consequences, mounting difficulties in the final assembly line in order to obtain the precision and tolerances required and a big lead time thereby slowing the production rate.

The present invention is intended to provide a solution to this problem.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an attachment system between an aircraft component, such as a vertical tail plane, and an aircraft fuselage allowing a simplified mounting process of the aircraft component onto the aircraft fuselage.

It is another object of the present invention to provide an attachment system between an aircraft component, such as a vertical tail plane, and an aircraft fuselage allowing the loads from the aircraft component to be transferred directly into the fuselage structure.

These and other objects are met by providing an attachment system for attaching a component, such as a vertical tail plane, to the fuselage of an aircraft; the aircraft component being structured as a box comprising front and rear spars, ribs extending from the front spar to the rear spar and a skin; the fuselage comprising a skin and frames; the system comprising in the aircraft component a plurality of intermediate spars arranged to be attached to the fuselage frames and in the fuselage a mounting arrangement suitable for receiving the intermediate spars and for allowing attachment of the aircraft component to the fuselage frames.

In a preferred embodiment, the plurality of intermediate spars are arranged to be attached to contiguous fuselage frames, whereby an attachment system that optimizes the mounting arrangement in the fuselage is achieved.

In another preferred embodiment, the plurality of intermediate spars are attached by one of its ends to any of the front and rear spars or to any of the ribs, whereby an attachment system that facilitates the integration of the intermediate spars in the box structure is achieved.

In another preferred embodiment, the mounting arrangement comprises a plurality of access doors in the fuselage skin allowing the correct positioning of the aircraft component onto the fuselage. Hereby it is achieved an attachment system that facilitates the assembly of the aircraft component onto the fuselage because the mounting operation is reduced to the positioning of the aircraft component on the place foreseen for it inside the fuselage.

In another preferred embodiment the attachment system also comprises two longitudinal elements that are joined both to the fuselage skin and to the skin of the aircraft component. Hereby it is achieved an attachment system that includes complementary means for the transfer of loads of an easy implementation.

In another preferred embodiment the fuselage frames and the vertical tail plane intermediate frames have a C-shaped transversal section and the intermediate spars are arranged in a manner so that the lower part of its webs can be attached to the webs of the frames by mechanical means. Hereby it is achieved an attachment system that facilitates the fastening process between the intermediate spars and the frames.

In another preferred embodiment, the frames and the intermediate spars having a C-shaped transversal section are arranged in a manner so that the flanges of contiguous frames and intermediate spars are oppositely oriented. Hereby it is achieved an attachment system that optimizes the assembly of the vertical tail plane onto the fuselage.

Other characteristics and advantages of the present invention will be clear from the following detailed description of the embodiments illustrative of its object in relation to the attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of an attachment system between a vertical tail plane and a fuselage according to the present invention.

FIG. 2 is schematic perspective view showing how the vertical tail plane spars are attached to the fuselage frames according to an embodiment of the present invention.

FIG. 3 is a separated schematic perspective view of the vertical tail plane according to the present invention to be attached to the aircraft fuselage.

FIG. 4 is a separated schematic lateral view of the aircraft fuselage according to the present invention to which the vertical tail plane will be attached.

FIG. 5 is a schematic transversal section showing the vertical tail plane attached to the aircraft fuselage according to the present invention.

FIG. 6 is a schematic perspective view of the mounting operation of the vertical tail plane into the aircraft fuselage according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the aircraft industry it is quite frequent that different aircraft components are manufactured in different places under very strict tolerance requirements for avoiding problems in the final assembly. These requirements are particularly relevant for components made of composite materials.

The basic idea of the present invention is a re-design of the structural integration of an aircraft component such as a vertical tail plane with the aircraft fuselage intended both to facilitate its assembly and to provide an efficient load transmission to the fuselage structure. This re-design involves new means in the vertical tail plane and in the aircraft fuselage.

In the embodiment illustrated in FIGS. 1 through 6, it can be seen that the internal structure of the vertical tail plane 11 is a conventional box structure comprising a front spar 13, a rear spar 14, ribs 15 extending from the front spar 13 to the rear spar 14, and a skin 17 stiffened by stringers 18. In addition to this conventional structure and according to the present invention, the vertical tail plane 11 also comprises intermediate spars 23, attached by one of its ends to any of the front and rear spars 13, 14 or to any of the ribs 15, duly arranged to be attached by its lower section, extended outside the box structure, to the fuselage frames 33.

The structure of the fuselage 27 is a conventional structure comprising a skin 31 stiffened by stringers (not shown in the Figures) and frames 33 incorporating, according to the present invention, a mounting arrangement for the integration of the vertical tail plane 11 comprising access doors 45 in the fuselage skin 31 for facilitating the vertical tail plane 11 mounting operation over the fuselage 27 and to provide room for performing the fastening operation between the intermediate spars 23 and the frames 33.

The attachment between the vertical tail plane 11 and the fuselage 27 is done fastening the intermediate spars 23 to the frames 33 by means of rivets 39 and also attaching the vertical tail plane skin 17 to the fuselage skin 31 through at least two longitudinal elements referred to as “doublers” 49 which are riveted both to the vertical tail plane skin 17 and to the fuselage skin 31 (see FIG. 5).

In a preferred embodiment, particularly illustrated in FIG. 2, the intermediate spars 23 have a C-shaped transversal section with webs 25 and flanges 27, and the frames 33 have a C-shaped transversal section with webs 35 and flanges 37. In its upper section, frames 33 have a greater web height defining a reinforced section for receiving the loads transferred by the intermediate spars 23. The contiguous frames 33 and the intermediate spars 23 are arranged in an opposite orientation of its C-shaped transversal sections.

As illustrated in FIG. 6, the vertical tail plane 11 is mounted on the fuselage 27 in a vertical assembly direction indicated by arrow 55. After the vertical tail plane 11 is placed in its position inside the fuselage 27, a fastening operation is performed between intermediate spars 23 and frames 33, and, finally, a fastening operation is performed between doublers 49 and vertical tail plane skin 17 and fuselage skin 31.

The attachment system between vertical tail plane 11 and fuselage 27, according to the present invention, allows a reduction of the number of joints that contributes to a simplification of the assembly procedure and to a cost reduction, and provides a proper load path redundancy to assure the safety of the vertical tail plane junction.

Although the present invention has been fully described in connection with the embodiments described and illustrated herein, it is evident that modifications may be introduced within the scope thereof, not considering this as limited by these embodiments, but by the contents of the following claims. 

1. An attachment system for attaching a component (11) to the fuselage (27) of an aircraft; the component (11) being structured as a box comprising front and rear spars (13, 14), ribs (15) extending from the front spar (13) to the rear spar (14) and a skin (17); the fuselage (27) comprising a skin (31) and frames (33); characterized by comprising: in the component (11), a plurality of intermediate spars (23) arranged to be attached to the frames (33); and in the fuselage (27), a mounting arrangement suitable for receiving the plurality of intermediate spars (23) and for allowing the attachment of the fuselage to the frames (33).
 2. The attachment system according to claim 1, characterized in that the plurality of intermediate spars (23) are arranged to be attached to contiguous frames (33).
 3. The attachment system according to claim 1, characterized in that the plurality of intermediate spars (23) are attached by one of its ends to any of the front and rear spars (13, 14) and optionally to any of the ribs (15).
 4. The attachment system according to claim 1, characterized in that the mounting arrangement comprises a plurality of access doors (45) in the fuselage skin (31) allowing the correct positioning of the component (11) on the fuselage (27).
 5. The attachment system according to claim 1, wherein the attachment system is further characterized as comprising at least two longitudinal elements (49) constructed to be joined to the fuselage skin (31) and to the skin (17) of the component (11).
 6. The attachment system according to claim 1, characterized in that the component (11) is a vertical tail plane.
 7. The attachment system according to claim 6, characterized in that the frames (33) and the intermediate spars (23) have a C-shaped transversal section; in that each of the frames (33) comprises a web (25) and each of the intermediate spars (23) comprises a web (35); and in that the intermediate spars (23) are arranged in a manner so that the lower part of their webs (25) can be attached to the webs (35) of the frames (33) by mechanical means.
 8. The attachment system according to claim 7, characterized in that each of the frames (33) comprises a flange (37) and each of the intermediate spars (23) comprises a flange (27), and in that the frames (33) and the intermediate spars (23) are arranged in a manner so that the flanges (37) of the contiguous frames (33) and the flanges (27) of the plurality of intermediate spars (23) are oppositely oriented.
 9. The attachment system according to claim 2, characterized in that the plurality of intermediate spars (23) are attached by one of its ends to any of the front and rear spars (13, 14) and optionally to any of the ribs (15).
 10. The attachment system according to claim 9, characterized in that the mounting arrangement comprises a plurality of access doors (45) in the fuselage skin (31) allowing the correct positioning of the component (11) on the fuselage (27).
 11. The attachment system according to claim 10, wherein the attachment system is further characterized as comprising at least two longitudinal elements (49) constructed to be joined to the fuselage skin (31) and to the skin (17) of the component (11).
 12. The attachment system according to claim 11, characterized in that the component (11) is a vertical tail plane.
 13. The attachment system according to claim 12, characterized in that each of the frames (33) and each of the intermediate spars (23) have a C-shaped transversal section; in that each of the frames (33) comprises a web (25) and each of the intermediate spars (23) comprises a web (35); and in that the intermediate spars (23) are arranged in a manner so that the lower part of their webs (25) can be attached to the webs (35) of the frames (33) by mechanical means.
 14. The attachment system according to claim 13, characterized in that each of the frames (33) comprises a flange (37) and each of the intermediate spars (23) comprises a flange (27), and in that the frames (33) and the intermediate spars (23) are arranged in a manner so that the flanges (37) of the contiguous frames (33) and the flanges (27) of the intermediate spars (23) are oppositely oriented. 